Surface finishing, also known as micromachining, microfinishing, and short-stroke honing, relates to a broad range of industrial processes that alter the surface of a manufactured item. For example, surface finishing processes may be employed to improve or modify appearance, geometry, adhesion or wettability, solderability, corrosion resistance, tarnish resistance, chemical resistance, wear resistance, hardness, electrical conductivity, burrs and other surface flaws, and control the surface friction. Well known mechanical surface finishing processes include, e.g., abrasive blasting, sandblasting, burnishing, grinding, mass finishing processes, tumble finishing, vibratory finishing, polishing, buffing, or lapping. It has been proven that surface finishing certain parts makes them more durable. For example, if the teeth in a gear are superfinished they can last up to four times as long. Other commonly superfinished mechanical parts include steering rack components, transmission components, fuel injector components, camshaft lobes, hydraulic cylinder rods, bearing races, needle rollers, and sharpening stones and wheels.
In certain applications, surface finishing processes are utilized to finish surfaces of mechanical components and equipment in order to gain improved performance and lubricant-related efficiencies. For example, achieving high energy efficiency in, e.g., an internal combustion engine, as well as other mechanical systems, often requires that certain lubricated components have very low surface roughness. This is achieved by removing just the thin amorphous surface layer left by the last process with an abrasive stone or tape; this layer is usually about 1 μm in magnitude. Surface finishing, unlike polishing which produces a mirror finish, creates a cross-hatch pattern on the work-piece, and can give a surface finish of 0.01 μm.
Recent advances in additive manufacturing (AM) have resulted in its emergence as a potential alternative to traditional metal manufacturing. AM processes include technologies that build 3D objects by adding layer-upon-layer of material, whether the material is plastic, metal, concrete or even tissue. The term AM encompasses 3D Printing, Rapid Prototyping (RP), Direct Digital Manufacturing (DDM), layered manufacturing and additive fabrication.
Additive manufacturing processes, e.g., 3D printing, can advantageously produce finished materials and structural components, often in a single manufacturing step, and often at low cost. However, the raw surfaces of such AM materials have typical surface roughness that are significantly greater than the roughness of surfaces typically used in lubricated mechanical components found in diverse mechanical systems, including internal combustion engines. As such, 3D-printed materials having rough surfaces would be seriously disadvantaged in providing maximum energy efficiency. As such, most mechanical components requiring smooth surface finishes, such as, for example internal combustion (IC) engine parts, are made with traditional mechanical surface finishing processes such as those described above.
Moving mechanical components typically require lubricating oils. Lubricating oils perform numerous functions, including, for example, reducing friction and wear of numerous parts in moving contact with each other, such as engine piston rings and cylinder walls, valves, cams, bearings, etc. The same can be said for lubricating oils other than engine oils, such as transmission fluids, hydraulic oils, gear oils, turbine oils, functional fluids, industrial oils, which all function to lubricate parts in moving relationship with each other. Lubricant-related energy efficiency performance is highly desirable due to increasingly stringent governmental regulations for vehicle fuel consumption and carbon emissions. At the same time, lubricants need to provide a substantial level of wear control and high temperature performance due to the proliferation of smaller and higher output modern engine designs.
Lubricant-related performance characteristics such as wear control, high and low temperature deposit control, high temperature varnish control, and fuel economy are extremely advantageous attributes. However, it would be advantageous to avoid the additional step of surface finishing mechanical components prior to use in lubricated systems, e.g., combustion engines. In order to greater enhance energy efficiencies, there exists in the art an ongoing need for lubricant compositions that achieve wear, deposit, and varnish control, while also maintaining energy efficiency over a broad temperature range when in contact with a diverse range of materials and surface finishes, including in AM materials.